1. Field of the Invention
This invention relates to a blood purification device for use in the treatment of immune diseases, cancer diseases, familial hypercholesterolemia, hepatic diseases and renal diseases, among others.
2. Description of the Prior Art
Recently, much attention has been focused on the plasma exchange therapy which can really produce a significant effect in the treatment of immune diseases, cancer diseases, familial hypercholesterolemia, hepatic diseases, renal diseases and so forth, including autoimmune diseases and graft rejection. The effect is supposedly due to the removal of causative substances in the blood, such as antibodies, immunosuppressive factors, low-density lipoprotein (LDL), metabolite-bound proteins, hepatotoxic and nephrotoxic substances, together with the plasma. However, in the plasma exchange therapy, it is necessary to supplement normal human plasma or human serum albumin instead of the discarded patients' plasma and therefore can hardly be applied to the treatment of a large number of patients. The therapy is also wasteful because useful components are also removed together with unnecessary disease-causing substances.
On the other hand, the blood purification method using an adsorbent has an advantage that a supplemental fluid is scarcely needed because unnecessary components alone are removed. However, when activated carbon or a porous resin is used as the adsorbent, low-molecular-weight substances such as creatinine and uric acid can be adsorbed but those causative substances that have a high molecular weight can hardly be removed, so that a satisfactory therapeutic effect cannot be produced. Although some porous resins (e.g. Rohm & Haas' porous resin "Amberlite.RTM. XAD-7") can adsorb proteins having a medium or higher molecular weight, they have a disadvantage that they also adsorb useful components such as vitamins and saccharides or that impurities from the manufacturing process are leached out or minute particles are frequently formed, hence they are less practicable.
As a result of intensive research to overcome these problems, the present inventors previously have found that a porous material having a mean pore diameter of 30-3,000 angstroms with a sharp pore size distribution and preferably having the silanol group on the surface can absorb proteins selectively and have applied for a patent (Ser. No. 250,630). However, it has lately been found that such a porous material as porous glass is generally has a crushed form and each granule thereof has sharp edges, so that, when used in the direct blood treatment, such a material causes decrease in leukocyte or platelet count. Moreover, when crushed granules are packed in a column and the blood or plasma is passed therethrough, the pressure loss within the column increases with the lapse of time in a manner unfavorable to the prolonged blood treatment. As a result of further research in view of the above, it has now been found that the use of porous granules spherical in shape can overcome the above-mentioned disadvantages, and this finding has led to the present invention.